In the installation and maintenance of electrical distribution systems, such as distribution transformers or substations, it is necessary to connect respective pairs of leads or wires and to maintain a solid mechanical retention of the wires as well as a good electrical connection therebetween despite fluctuations in the line current or severe weather conditions.
The wires may run from around 1/16 inch in diameter to around 5/8 of an inch for plier-applied connectors, depending upon the particular distribution system or subsystem. The smaller sized wires are usually made of aluminum or copper or a combination thereof for normal household currents; and the larger wires, which are primarily intended for outdoor distribution systems, are usually made of aluminum provided with a steel wire core.
The aluminum wire tends to "creep", that is, it lacks good dimensional stability; and the particular connector between the wires may not effectively compensate for that dimensional instability in the wire material.
The existing connectors used in junction boxes for residential duty and the like usually include a pair of clamping members drawn up tight by means of a screw therebetween. The screw may vibrate loose and, besides, there is no built-in compensation for material creepage.
In heavy-duty applications, the existing connectors may use a power actuated portable tool to drive a wedge into the connector, thereby retaining the wires mechanically and making the necessary electrical connection therebetween. Such a tool is supplied by AMP Incorporated (of Harrisburg, Pa.) under its trademark "AMPACT".
While perfectly suitable for the purposes intended, nevertheless, this is a special tool which may not be readily available to installers or maintenance personnel out in the field. Besides, each "shot" of this tool requires a cartridge, the cost of which may run around $1.00.